Unformatted text preview: 08Ch08.qxd 9/18/08 11:03 AM Page 657 SECTION 8.3 Cylindrical Pressure Vessels Problem 8.3-3 An inflatable structure used by a traveling 657 Longitudinal seam circus has the shape of a half-circular cylinder with closed ends
(see figure). The fabric and plastic structure is inflated by a
small blower and has a radius of 40 ft when fully inflated. A
longitudinal seam runs the entire length of the “ridge” of the
If the longitudinal seam along the ridge tears open when it
is subjected to a tensile load of 540 pounds per inch of seam,
what is the factor of safety n against tearing when the internal
pressure is 0.5 psi and the structure is fully inflated? Solution 8.3-3 Inflatable structure Half-circular cylinder
r 40 ft 480 in.
Internal pressure p 0.5 psi
T tensile force per unit length of longitudinal seam
Seam tears when T Tmax 540 lb/in.
Find factor of safety against tearing. CIRCUMFERENTIAL STRESS (EQ. 8-5)
t thickness of fabric Actual value of T due to internal pressure
T s1t pr (0.5 psi)(480 in.) s1t 240 lb/in. FACTOR OF SAFETY
T 540 lb/in.
240 lb/in. 2.25 ; Problem 8.3-4 A thin-walled cylindrical pressure vessel of radius r is subjected
simultaneously to internal gas pressure p and a compressive force F acting at the
ends (see figure).
What should be the magnitude of the force F in order to produce pure shear
in the wall of the cylinder? F F Solution 8.3-4 Cylindrical pressure vessel
STRESSES (SEE EQ. 8-5 AND 8-6):
r Radius p Internal pressure pr
t s2 pr
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- Tensile strength, longitudinal seam